This invention relates to a process for the production of flame-retardant polyurethane products by reacting salt-forming compounds in a polyol and/or a polyisocyanate, then reacting the polyol and polyisocyanate.
The production of polyurethane products is well known in the Arts and many types of flame-retardant chemicals have been used in the process. It is also known in the Arts that salts of phosphoric acid are useful as a flame-retardant, but when added to the polyurethane products, they take a large amount to do any good as a flame-retardant; therefore, they are not very useful. In the novel process of this invention, only a small amount of salts of phosphorus and-or halogen salts are necessary to produce a flame-retardant product because the molecules of the salts are small and very well distributed throughout the product. In the process of this invention, low-cost and readily available compounds are utilized and there is an improvement in the cost of the product, in the amount of flame-retardant needed, and in the production of inexpensive flame-retardant compounds.
While not wishing to be bound by any theory of operation, it appears that there may also be some reaction of the salt-forming compounds with the polyol or polyisocyanate to give a much better and more stable distribution of salts, thereby proving flame-retardant properties. Any excess of basic salt-forming compounds may be used as a filler or may be a reactant in the process. It takes an amount at least 5 to 10 times more when the salt of phosphorus-containing compound is added to the reactive mixture to produce polyurethane products than it does when the salt is produced as outlined in this invention. The flame-retardant salt produced by the process of this invention is less expensive and at least equal to, or better than, the commercially available flame-retardant agents for polyurethane products in flame-retardant properties.